NAPA Helps Answer: What is the Environmental Impact of Asphalt?

The asphalt industry has a long history of working with federal regulatory agencies, including the Environmental Protection Agency (EPA) and OSHA. Since the early 1990s, the EPA has done extensive testing on asphalt plant emissions and in 2002 removed this industrial sector from the “major source” category, identifying that emissions from asphalt plants are not an area of concern. (1) NAPA is the National Asphalt Pavement Association.

Understanding Reclaimed Asphalt Pavement (RAP) as a Clean Fill Material

In 2019, more than 97 million tons of RAP and 921,000 tons of reclaimed asphalt shingles (RAS) were used in new asphalt pavement mixes in the U.S. That year about 139 million tons of RAP and RAS were stockpiled for future use across the country. Reusing RAP in future pavements saved nearly 60 million cubic yards of landfill space during 2019.  (2)

As America’s biggest recycler, millions of tons of asphalt pavement material is reclaimed each year during road widening and resurfacing projects, and nearly all of that material is reused. Incorporating reclaimed asphalt pavement (RAP) into new pavements reduces demands for virgin asphalt binder, helping to keep costs down as well as improving the environmental footprint of projects.

Not all RAP is recycled into new asphalt pavements, however. Occasionally, the question arises as to whether or not RAP can be used as “clean fill.” Although obviously not the highest and best use of this vital resource, regulations regarding when and where RAP can be placed as fill material vary from state to state and can be complex. In most instances, RAP falls under state solid-waste requirements and purview.

Material that is Recycled is Not Considered Solid Waste

Because state environmental agencies often have more restrictive solid-waste disposal regulations than the federal Environmental Protection Agency, it is important to understand how RAP is defined. U.S. EPA classifies RAP as construction and demolition (C&D) debris that is part of the federal solid-waste chain. Federal regulations also identify that if materials are “recycled,” then they are not considered solid waste. However, there is a “speculative accumulation” federal definition that requires a 75 percent annual “turnover” to maintain the recycled material classification vs. solid waste.

There are NO Harmful Compounds Leached from RAP

RAP is not, and never has been, considered a “hazardous” solid waste. Years of leaching studies show that there are no harmful components leached from RAP under the most stringent waste definition extraction conditions. (See NAPA Special Report 190: “Reclaimed Asphalt Pavement (RAP) Stockpile Emissions and Leachate.”) In general, it is acceptable for RAP to be used as a road material — as part of the base, recycled back into pavement, etc. — both from a federal and state perspective. Although U.S. EPA does not appear to have a strict definition of “clean fill”, specific requirements do apply to solid-waste materials applied to land.

The bottom line is that each state’s environmental agency will likely dictate whether or not RAP can be used as a clean fill material. Under normal use and circumstances, RAP should never be considered as hazardous waste. (3)

See Also

Sources:

  1. https://www.asphaltpavement.org/expertise/health-safety/environmental
  2. Williams, B.A., Willis, Richard & Shacat, Joseph (2019). Asphalt Pavement Industry Survey on Recycled Materials and Warm-Mix Asphalt Usage: 2018 (IS 138) National Asphalt Pavement Association, Greenbelt, Maryland.
  3. https://www.asphaltpavement.org/uploads/documents/SR204-RAP_as_Clean_Fill.pdf

Environmental & Sustainability Terms

  • GHG
    • Greenhouse Gases
    • Many gasses have global warming properties (GHG). The majority of GHG emissions from industrial, commercial, and institutional activities are CO2, CH4, and N2O.
  • CO2
    • Carbon Dioxide
    • Carbon dioxide is a natural greenhouse gas, commonly produced by the air we exhale. At higher levels, CO2 affects productivity, sleep and infectious disease.
    • Some believe carbon dioxide and methane are the biggest drivers of global warming related to human activities
    • CO2 is the reference gas for Global Warming Potential (GWP) compared to other GHG gases. GWP = 1
  • CH4
    • Methane
    • Methane is a colorless, odorless, flammable gas that is the simplest hydrocarbon and is the major constituent of natural gas
    • Some believe carbon dioxide and methane are the biggest drivers of global warming related to human activities
    • CH4 GWP = 25 (25 times greater warming potential than CO2)
  • N2O
    • Nitrous Oxide
    • Nitrous oxide, commonly known as “laughing gas,” is a chemical compound with the chemical formula N2O.
    • It is a colorless non-flammable gas at room temperature, with a pleasant, slightly sweet odor and taste.
    • It is used in surgery and dentistry for its anesthetic and analgesic effects.
    • Some believe it may be the most important greenhouse gas after methane and carbon dioxide and the biggest human-related threat to the ozone layer
    • N2O GWP = 298 (298 times greater warming potential than CO2)
  • CO2e
    • Carbon dioxide equivalent
    • This is the number of metric tons of CO2 emissions with the same global warming potential as one metric ton of another greenhouse gas, and is calculated using Equation A-1 in 40 CFR Part 98
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Sustainable Infrastructure Project in Gogebic County Michigan

Cold In-Place Recycling

In 2021, the Gogebic County Road Commission constructed their first recycling job.  The first phase, which was approximately 3 miles of the Lake Road Cold In-Place Recycle (CIR) project, was finished in 2021. There are approximately 2.5 miles that are projected to finish in 2022. This final section of the roadway to be completed in 2022 is to repave the stretch of road from Little Girls Point to the Wisconsin border.

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Pavement Preservation Leads to a More Sustainable Infrastructure

Pavement preservation is a cost-effective and greener approach to getting the most life out of your roads and making taxpayer dollars go further. In addition to cost efficiency, a pavement preservation approach is known to produce fewer greenhouse gas emissions (GHG), consume less energy, and provide faster application times than the alternative conventional approach.

A well-implemented pavement preservation approach achieves maximum efficiency by increasing the average condition of your pavement while decreasing your average spending per square yard. Pavement Preservation treatments are known for their ability to ensure quality with minimal effect on your budget and the environment.

Compare cost savings and environmental impact by treatment

An approach to pavement management that applies a robust toolbox of pavement preservation and recycling treatments will save time, money, while also reducing environmental impact over the long term. By using a PPRA calculator you are able to see average data comparing the cost and environmental savings of preservation and recycling techniques, compared to conventional reconstruction, mill and fill, or thin overlays.

Critical Concept !!

Every year, every mile of your network loses 1 mile-year of life. To avoid losing ground, the roadway owner must design a treatment plan that adds 500 mile-years of life or more! Over the first 75% of a road’s life, it will drop 40% in quality. Over the next 12% of its life, it will drop another 40% in quality. All roads pass a point of accelerated deterioration – past this point, costly rehab and reconstruction are the only options.

Worst – First Approach

Many agencies are learning that the use of limited funds toward a “Worst First” Approach accelerates the decline of their overall network, as miles of good roads go untreated each year. A conventional method of pavement management uses limited budgets to address the most deteriorated roads first. Miles of good roads go untreated each year, accelerating the decline of the overall network.

Many agencies are identifying pavement management strategies that use limited resources more efficiently, and designing treatment plans that reallocate budgets to make incremental network gains (instead of losses) each year. Use our Remaining Service Life tool to find out if your treatment plan is adding or subtracting life from your network.

Optimized Approach

By considering an Optimized Approach, which reallocates funds across more efficient strategies to keep good roads good and help you get ahead of the curve.

Understanding Remaining Service Life (RSL) is critical to designing a treatment plan that stretches your budget further and reverses the trend of a deteriorating network.

Pavement Preservation Methods’ ROI (Spend $1 Save $6)

There are two basic ideas to follow when choosing a Pavement Preservation Strategy:

1. Prioritize roads that are in fair-to-good condition. Why spend money on a road that is in decent condition? It is the most effective way to stretch dollars while also improving overall pavement condition. If you put your budget toward inexpensive, frequent treatments to semi-distressed roads, you will find the most savings as a whole. 

2. Applying a pavement preservation method maximizes pavement quality & lifespan.  Oxidation and moisture can take hold of a pavement within the first 2 years of its life, losing elasticity and becoming frail over time. These issues can result in surface raveling, cracking, potholes, and eventually pavement failure.

By performing a simple early pavement preservation system combined with a high-quality product the pavement can be preserved resulting in superior and longer-lasting roads. Maximizing your investment over time. Pavement preservation techniques not only provide the best way to maintain road integrity and durability, but they also reduce motorist delays and provide longer-lasting, safer roads.

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To learn more about Asphalt Materials Pavement Preservation Projects, visit our products page:

https://asphalt-materials.com/products/

Sources for this Article and Other Resources Available to Learn More

https://roadresource.org/preservation

PPRA’s RSL Calculator – Ready To Optimize Your Network?

https://roadresource.org/network/rsl_calc

https://roadresource.org/preservation/calculator

About PPRA:

The Pavement Preservation & Recycling Alliance (PPRA) provides a collective space to bring industry and agency together for the advancement of sustainable, eco-efficient, and innovative pavement applications.

Joining together resources from the Asphalt Emulsion Manufacturers Association, the Asphalt Recycling & Reclaiming Association, and the International Slurry Surfacing Association, PPRA unites a network of members dedicated to: “Better roads today. Stronger networks tomorrow.” Jointly, PPRA assists agencies by providing a centralized repository for comprehensive information related to pavement preservation and asphalt recycling and reclaiming. PPRA seeks to help agencies at the state, county, and local levels to make the right choices for their road networks and be the best possible stewards of their roads and of taxpayer dollars.

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